Note: this site last updated in 2006
An article from "The Molecules of HIV" (c) Dan Stowell
The membrane is an approximately spherical layer that surrounds the inner core. It is made of the same type of substances (lipids) as cell membranes. The "matrix protein", p17, lines the inner surface of the membrane.
On the surface of the membrane are many "spikes" made of envelope protein (env). These spikes are important because they are used to latch on to potential host cells - without them the virus particle would normally just float around and not do very much at all.